Using/by using

2 answers

2

Expanding on Tolley's answer, you can:

"cut with a knife."

"cut using a knife"

"cut by using a knife"

All three are acceptable, but carry slightly different emphasis in American English. In the first example, the emphasis is on what was cut -- in your case, the apple -- and the knife is more of an afterthought. The second and third place a bit more emphasis on what did the cutting -- the knife -- and might be used in situations where a choice of cutting tools was available. "He cut the apple using the knife and not the hacksaw." Adding "by" further emphasizes "knife". The "by using" construction is less common, unless the extra emphasis is desired.

The first, in this case, means "by a knife" or "through a knife", which each mean "that the knife was a means by which the cutting took place". The second literally means that the cutter happened to be using a knife at the time that he or she was cutting an apple--not necessarily that the knife was cut with an apple, although it would most likely be interpreted that way in most contexts. Finally, in the third, "by using the knife" literally means "using of the knife is a means by which the cutting took place". the act of using the knife".